gravity fed hot water cylinder

[moliver34]

Ive gotta gravity fed hot water cylinder; central heating fully pumped!

The pipes from the boiler [oil fired] get hot, but the water in the cylinder remains cold;

Should I assume there is a blockage in the pipe work to the cylinder; Im told this is quite a common fault on gravity fed systems. There is also a lot of black magnite sludge in the system

Any idears on how to clear it, besides a power flush as the cylinder looks old, and might not withstand it!

 

[JohnD]

If you bleed the highest level vent on a radiator (or better, the feed to the cylinder) does water squirt out vigorously?

When you look in the Feed & Exansion tank, how much water does it have in it?

If you draw a pint of water out of the drain cock, does the same amount flow into the F&E tank?

Have you got a strong magnet?

 

[gas4you]

First place I'd look if you have followed johnd advice and are sure you have a blockage is the T where the cold fill joins the gravity return, after that the T to the vent.